1. Field of the Invention
This invention relates to a composition for dielectric porcelain, and a dielectric porcelain and a capacitor by use of said composition.
2. Related Background Art
In the prior art, there have been employed, as the dielectric member to be used for capacitors, etc., porcelains comprising BaTiO.sub.3, BaSnO.sub.3 , CaTiO.sub.3 or a solid solution having other components added to these double oxides as the main component, or these materials modified with various additives. However, these porcelains are required to be sintered at a high temperature of 1300.degree. to 1400.degree. C. and therefore, for example, when applied for a laminated capacitor, there ensues the problem that no silver type electrode can be used as the internal electrode, and it has been sought to develop a porcelain which can be sintered at lower temperatures.
Also, in the dielectric porcelain of the prior art, if the dielectric constant at around normal temperature is made greater, the temperature coefficient of dielectric constant also becomes greater; on the contrary, if the temperature coefficient of dielectric constant at around normal temperature is made smaller, the dielectric constant also becomes smaller. Thus, it has been difficult to obtain a porcelain with a great dielectric constant and a small temperature coefficient of dielectric constant.
Further, in the case when the porcelain has a strong dielectric property, the Curie point is around normal temperature due to modification with an additive, whereby mechanical strength will be lowered due to phase transfer at this temperature, and there is also involved the problem that it cannot be used as a functional element without difficulty.